Structure-properties relationships in alkaline treated rice husk reinforced thermoplastic cassava starch biocomposites.

The study focuses on structure-properties relationships in thermoplastic cassava starch (TPS) based biocomposites comprising 5-20 wt% of untreated and treated rice husk (RH). Alkaline treatment with 11% w/v NaOH removed the hemicellulose layer of RH as confirmed by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and resulted in a larger population of -OH groups exposing on the fibril surface. Consequently, the filler-matrix interactions between treated RH and TPS were enhanced, although Brunauer-Emmett-Teller (BET) surface area analysis indicated that the surface area of treated RH was not increased. Interestingly, the biocomposites contained 20 wt% treated RH showed substantially improved tensile strength by a factor of 220% compared to the neat TPS. The biocomposite at 15 wt% treated RH showed high water absorption. TPS with all treated RH contents showed high biodegradation rate, while the thermal stability of the TPS/treated RH biocomposites was slightly decreased. These novel composites showed promising properties for applications as absorbents.